#

# Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

# All rights reserved.

# This component and the accompanying materials are made available

# under the terms of "Eclipse Public License v1.0"

# which accompanies this distribution, and is available

# at the URL "http://www.eclipse.org/legal/epl-v10.html".

#

# Initial Contributors:

# Nokia Corporation - initial contribution.

#

# Contributors:

#

# Description: 

#

import sys

import logging

import inspect

def load_plugin_classes(entry_point_group, base_class):

    """

    Load plugin classes from plug-in entry points.

    @param entry_point_group: Entry point group from which to load

        classes. Each entry point is expected to be an iterable of

        plugin class instances.

    @param base_class: The base class that every loaded class must inherit.

    @return: List of loaded plugin classes.

    """

    log = logging.getLogger('cone')

    log.setLevel(logging.DEBUG)

    validator_classes = []

    import pkg_resources

    working_set = pkg_resources.WorkingSet(sys.path)

    for entry_point in working_set.iter_entry_points(entry_point_group):

        class_list = entry_point.load()

        # Make sure that the class list is a list

        try:

            class_list = [c for c in class_list]

        except:

            log.warn("Entry point %s:%s is not iterable (%r)" % (entry_point_group, entry_point.name, class_list))

            continue

        for i, cls in enumerate(class_list):

            if not inspect.isclass(cls):

                log.warn("Object %d from entry point %s:%s is not a class (%r)" % (i, entry_point_group, entry_point.name, cls))

            elif not issubclass(cls, base_class):

                log.warn("Object %d from entry point %s:%s is not a sub-class of %s.%s (%r)" \

                         % (i, entry_point, entry_point.name,

                            base_class.__module__,

                            base_class.__name__,

                            cls))

            else:

                msg = "Validator class %r loaded from egg entry point %s:%s, item %d" % (cls, entry_point_group, entry_point.name, i)

                log.debug(msg)

                #print msg

                validator_classes.append(cls)

    return validator_classes

def filter_classes(classes, filter):

    """

    Filter the given list of validator by the given ProblemTypeFilter object.

    @param classes: The class list for filter. Each 

        class is assumed to have a PROBLEM_TYPES attribute that defines

        an iterable of the types of problems that the problem yields.

    @param filter: The filter object to use. Can be None, in which case

        the class list is simply returned back.

    @return: The filtered list.

    """

    if filter == None:

        return classes

    else:

        result = []

        for klass in classes:

            for problem_type in klass.PROBLEM_TYPES:

                if filter.match(problem_type):

                    result.append(klass)

                    break

        return result